Telephone-exchange system



L5UML229 Mug D J. W. GOODERHAM TELEPHONE EXCHANGE SYSTEM Filed July 28.1921 GII CSi

tary switch of the well-known type is employed. The thermionic relaydesignated by the numeral 57 is employed in the testing circuit as ameans for determining which current frequencies find a path over thecalling line and thereby determines the selection of a message registercorresponding to the particular substation callinO'. This thermionicrelay is of the well-known audion type and needs no further descriptionherein.

In the present disclosure the calling line is shown equipped with foursubstations, 1 to 4 inclusive, each substation being equipped with aband iilter designated as 5, 6, 7 and 8, respectively. The band filteroi' each substation comprises an impedance coil and a condenserdesignated, :tor example, at substation No. 1 as 9 and 10. The filter ofsubstation No. 1 is so tuned as to be resonant to one particular'frequency of current, the band filter 6 at substation No. 2 beingresonant to a certain other frequency and the band filters 7 and 8 andsubstations 3 vand 4 being also resonant to other fre quencies. Thus,when alternating current of four di'erent lfrequencies is impresseduponthe calling line, if at the time the receiver of substation No. 1 isoff its switch- `hook, current of three of the frequencies will passreadily through the filter `5, but the fourth frequency will not passtherethrough since the lter is resonant to such fourth frequency.

It will be assumed that the subscriber at substation No. 1 on thecalling line initiates a call by the removal of his receiver from itsswitchhook for the purpose of obtaining a connection with the line ofthe called subscriber 38. Upon the removal of the receiver fromi theswitchhoo'k, a circuit is established over the line conductors 11 and 12in the well-known manner, thereby causing the positioning of the wipers13 and 14 of the subscribers individual line switch upon the terminals15 and 16 of a district link circuit which terminates in the districtselector brushes 24 and 25.y Upon the extension of the calling line tothe district link, a circuit is established in the well-known mannerforthe sequence switch magnet 17 for advancing the sequence switch ofthe district selector out of its normal position into position 3, inwhich latter position the office sender 18 is associated with thecalling subscribers line overconductors 22 and 23 and the upper leftcontacts of cams and 21. The calling subscriber thereupon proceeds tooperate his sending dial 19 to set the registers of the sender 18 inaccordance with the oiiice and line designation of the desired line. "Inaccordance with the registration set up upon the otice'sender thebrushes 24'and 25 of the ldistrict selector are positioned in the`well-known manner upon terminals 26 and 27 of a trunk circuit extendingto an incoming selector switch represented by the brushes 32 and 33. Thesequence switch 17 is now advanced to position 11 and the otlice senderthereupon funetions to control the setting of the brushes 32 and 33 ofthe incoming selector and the brushes 34 and 35 of a final selector uponthe terminals 36 and 37 of the desired line 38, the control circuit overwhich these switches are controlled being` represented by the conductors28 and 29.

Following the setting or the selector switches and the extension of theconnection to the terminals of the desired line, the sequence switch 17of the district selector link is advanced into the talking position 13in the manner fully set forth in the aforementioned patent to F. A.Stearn and F. J. Scudder. As soon as sequence switch 17 reaches position12 a circuit is established for advancing the wipers oi' the message.register selector, which may be traced from battery through the armaturecontacts and winding-of stepping magnet 46, wiper 45, bank terminal 44,conductor 43, and thence toy ground at the lower right contact o'i cam42. As soon as the wipers ol the switch leave their normal restingposition, the initial starting circuit ol the switch is opened at bankterminal 44 and the movement o i the switch is continued by a circuitextending over wiper 45 and the' strapped bank terminals associatedtherewith, to ground.

1When the wiper 48 reaches the No. 1 terminal of its bank, a circuit isestablished from the source of alternating current 4S), over wiper 48and to ground through the primary winding of transformer 50, and currentis thereupon induced in the testing circuit 52, 53. This testing circuitmay be traced from the left terminal ol the secondary'winding oftranstfnmer 5t) through the lower winding oi transformer 5l, coilducto'r52, the lower left contact ol' cnin 2l. bank terminal 1G, wiper 14, lineconductor 12'to the filter 5, through the substation No. 1, lineconductor 11, wiper 13, terminal 15, the lower left 'contact ot cam 2t),conductor 53, and thence to the right termina] oi the secondary windingoi transtorlner 5t). Since, however, the iilter 5 is tuned to beresonant to current ot the frequency generated by the source 49, nocurrent Hows in the testing circuit above traced.

Then the wiper 48 advances to its No. 2 contact, the source or currentLl-9 is disconnected trom the primary winding oll transformer 50 and thesource ot current 5lis connected thereto. anti-resonant to current otthe frequency generated by the source 54, current Hows in thetestingcircuit and induces current through the upper winding ot transtormei.'51 to the input circuit of the thermionic re- Since the filter 5 is fi Ulay 57, the input circuit of the relay comprising the upper windingoftransformer 51, the filament 58 and the grid 59. As a result of thecurrent flowing in the input circuit ot the thermionic relay, currentlis caused to flow in the output circuit ot the relay from the posit-ivepole of battery through the left winding of' relay 60, the plate 61,thence to the lilainent 58 and to ground. Relay energizes in response tothe current 'liowing through its winding and closes a circuit for relay63 which may be traced from battery through the winding of relay 63,bank terminal 62, wiper 47 and thence to ground through the armaturecontact of relay 60.

In a similar manner as the wiper 48 advances to its third position bankterminal, the source of current 55 is inductively connected to the testcircuit and the therinionic relay 57 again responds, establishing` acircuit for the relay 65. lWhen the wiper 48 engages its No. 4 contact,the source of current 56 is inductively associated with the test circuitand causes the energiz'ation of relay 66. Relays 63, and 66, upon ener-kgizing, close locking circuits for themselves extending over their rightarmature contacts and conductor 64 to ground at the lower lett contactot cam 42. When the register selector advances its wipers to such a position that wiper 45 engages bank terminal 96, the register selector isarrested and awaits restoration which is accomplished when the callingsubscriber releases the connection upon the termina-tion of the conversation. It is to be noted that three relays 63, 65 and 66 have now beenlocked energized 'for preparing a circuit for the register,corresponding to the calling substation No. 1.

With sequence switch 17 in position 13, polarized relay 41 energizes assoon as the called subscriber 38 responds to the call. The circuit ofrelay 41 may be traced in aart over the Contact of cam 39, the leftcontact of cam 30, brush 24, bank terminal 26 and returning overterminal 27, brush 25, the lett contact of cam 31 and thence over thecontact of cam 40, current for operating relay 41 being s upplied tromthe link circuit associated with the incoming selector in the well-knownmanner. Upon the energization of relay 41 a circuit is established forrelay 68 which becomes effective as soon as cam 7() rotates to such aposition as to close its contact springs 69. This circuit may be tracedfrom battery through the con.- tact springs 69, the winding of relay 68,conductor 67, the armature contact of relay 41 and to ground over theupper lett contact of cam 42. Relay 68, upon energizing, locks throughits right-hand armature contact independent of cam springs 69 and at itslett arn'iature contact prepares a circuit tor relay 71 which iseffective as soon as cam rotates to such a position as to close contactsprings 72. Relay 71, upon energizing, locks over its right armaturecontact and the contact of cam 73, and at its lett-hand armature contactprepares an operating cir cuit for the selected message register'.

Upon the termination ot the conversation and the restoration ot thecalling' subscribers receiver to its switchhook, the supervisory relay74 deenergizes, closing a circuit for advancing the sequence switch 17oi' the district link out of its talking position inte position 17 inthe manner set forth in the aforesaid patent to F. A. Stearn and F. J.Scudder. With sequence switch 17 in position 17 the operating circuit otthe selected message register is established, which may be traced frombattery through the contact ot cam 81, the left armature and contact ofrelay 71, conductor 80, the lett armature and front contact of relay 66,the inner lett armatures and front contacts of relays and 63, the innerlett armature and back contact of relay 82, conductor 79, bank terminal78 and wiper 77 oi" the subscribers line switch and to ground throughthe wind ing 76 of the message register which is individual tosubstation No. 1. A circuit is also closed at this time from groundthrough the upper right-hand contact of cam 42,

conductor 75, bank terminal. 96, wiper 45 and through the winding ofstepping inagnet 46 for advancing the register selector into its normalposition. Following` message registration, the district selector' andthe other switches employed in the establishment of the connection arerestored in the well-known manner.

Had the calling substation No. 2 initiated the call, then since thelilter 6 associated with such substation is resonant to current oli' thefrequency generated by the source 54, current would flow over thetesting circuit 52, 53, only when the sources 49, and 56 are associatedtherewith.1 and consequently, through the operation of the thermionicrelay 57, locking relays 82, 65 and 66 would be operated. Thus when thesequence switch 17 reaches position 17 i'or registering a suc cesstulcall, the message register 86 indi- Vidual to the substation 2 would beoperated over a circuit extending from battery through the contact ofcam 81, the lett armature and contact of relay 71, conductor 80,

the left armature and front contact ot relay 66, the inner lett armatureand front contact of relay 65, the inner left armature and back contactof relay 63, armature contact 97 o'l' relay 82, conductor 83, terminal84, wiper 85, and thence to ground through the winding oi registermagnet 86. In a similar manner il: substation No. 3 initiates a callthe. thermio-nic relay 57 responds only when current from sources 49, 54and 56 'is applied to the testing circuit, and consequently, re-

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lays 66, 63 and 82 are operated. lith relays 66, 63 and 82 operated, themessage register 90 is selected for operation. lf the station No.i-.initiates the. call, thermionic relay 5? responds only `when currentfrom the sources 49, 54 and 55 is applied to the test circuit 52, 53, inWhich case, relays 82, 63 and 65 operate to prepare a circuit for themessage register 94.

Then two subscribers on rthe same line attempt to call simultaneously orhave their' receivers off their sivitchhoohs at the time theregistration test is made, all four relays 63, 65, 66 and 82 Willbecome. energized and no operating circuit for message registers iseffective. Such operated condition of all of these relays mio'ht beemployed to operate an alarm signal by connecting such a signal 86 tothe inner front contact of relay 82.

lVhile the invention has been disclosed in connection -with asubscribers line having four substations, it is obvious that it isequally applicable to lines having more than four substations, it onlybeing necessary to equip the additional substations with tuned circuitsdiffering from the tuned circuits supplied for the other substations andto provide additional sources of current, loching relays and messageregisters at the central office. Further, it is apparent that theinvention is not necessarily limited in its application to messageregistration, as the principles involved in the invention might beapplied to any circuit problem Where it would be desirable to determinewhich of a plurality of branch circuits is at. any time connected to amain or common circuit,y and in the appended claims this broaderinterpretation of the invention should be borne in mind.

lllhat is claimed is:

l, ln combination Wit-h a main circuit and a plurality of normally openbranches therefor, of an electrically selective device associatedWitheach of said branches, said several devices differing from eachother in their selectivity, means associated with each of said branchesfor eifecting its closure, a plurality of sources of current ofdifferent characteristics, means for associating said sources insuccession with said main circuit, and means selectively responsive tothe flow of said electric currents through. said selective device fordetermining which of said branches is closed.

2. In combination With a` main circuit and a plurality of normally openbranches therefor, of a frequency selective device associated with eachof said branches, said several devices ditfering from each other intheir selectivity, means associated With each of said branches foreffecting its closure, means for successively applying electric currentsof different frequencies to said main circuit, and means selectivelyresponsive to the flow of said electric currents through said selectivedevices for determining which of said branches is closed.

3. In combination `with a. main circuit and a plurality of normally openbranches therefor, of a filter associated with each of said branches,said several filters being tuned respectively to be selective tocurrents of dit'- ferent frequencies, means associated with each of saidbranches 'for effecting its closure, means for successively applyingelectric currents of different frequencies to said main circuit., andmeans selectively responsive to the flow of said electric currentsthrough said filters for determining which of said branches is closed.

Iil. ln combination with ay main circuit and a plurality of normallyopen branches therefor, of a filter associated with each of saidbranches, said several filters being tuned respectively to be resonantto currents of dilierent frequencies, means associated with each of saidbranches for effecting its closure, means for applying electric currentsof different frequencies in succession to said main circuit, and meansselectively responsive to the tloiv of said electric currents throughsaid filters for determining which of said branches is closed.

5. ln a signaling system, a .main circuit,

a plurality of normally open branches there for, a frequency selectivedevice associated with each of said branches, said several devicesdiffering from each other in their selectivity, means associated Witheach orf said branches for effecting its closure, means for applyingelectric currents of different frequencies in succession to said .maincircuit, a thermionie relay associated with said main circuit responsiveto the currents flowing thereover through said selective devices andsignaling means controlled by said relay for indicating which of saidbranches is closed C. ln a signaling system, a main circuit, a pluralityof normally open branches therefor, a filter associated with each ofsaid branches, said several filters being` timed respectively to beanti-resonant to currents of dillcrent frequencies, means associatedwith each of said branches for ellecting its closure, means for applyingelectric currents oi different frequencies in succession to said maincircuit, a thermionic relay associated with said main circuit responsiveto the currents flowing thereover through said filters and signalingmeans controlled by said relay for indicating which of said branches isclosed.

7. ln a signaling system, a main circuit, a plurality of normally openbranches therefor, a filter associated With each of said branches, saidseveral filters being timed respectively to be resonant to current ofdifferent frequencies, means associated with los) each of said branchesfor effecting its closure, means for applying electric currents ofdifferent frequencies in succession to said main circuit, a thermionicrelay associated with said main circuit and operated by current flowingthereover from any of said sources, a plurality of relays, means forassociating said relays in succession for operation by said thermionicrelay and signaling means selectively operable under the control of saidrelays for indicating which of said branches is closed.

S. In a signaling system, a main circuit, a plurality of normally openbranches therefor, a filter associated with each of said branches, saidseveral filters being tuned respectively to be resonant to current ofdifferent frequencies, means associated with each of said branches foreffecting its closure, sources of current of the frequencies to whichsaid filters are resonant, a thermionic relay associated with said maincircuit and operated by current flowing thereover through any one ofsaid filters from any of said sources, a plurality of relays controlledby said thermionic relay, a switching device for successivelyassociating said sources of current with said main circuit and saidrelays with said thermionic relay and signaling means selectivelyoperable under the control of said relays for indicating which of saidbranches is closed.

9. In a signaling system, a main circuit, a plurality of normally openbranches therefor, a filter associated with each of said branches, saidseveral filters being tuned respectively to be resonant to current ofdifferent frequencies, means associated with each of said branches foreffecting its closure, sources of current of the frequenciesv to whichsaid filters are resonant, a thermionic relay associated with said maincircuit and operated by current flowing thereover through any closedbranch thereof from such of said sources of current as are in theresonance range of the filter of said closed branch, a plurality ofrelays controlled by said thermionic relay, a switching device forsuccessively associating said sources of current with said main circuitand said relays with said thermionic relay and signaling meansselectively operablel under the control of said relays for indicatingwhich of said branches is closed,

10. In a signaling system, a main circuit, a plurality of normally openbranches therefor, a filter associated with each of said branches, saidseveral iilters being tuned respectively to be resonant to current ofdifferent frequencies, means associated with each of said branches foreecting its closure, sources of current of the frequencies to which saidfilters are resonant, a thermionic relay associated with said maincirciiit-and operated by current flowing over said main circuit throughany closed branch thereof from such of said sources of current as are inthe resonance range of the filter of said closed branch, a plurality ofrelays controlled by said thermionic relay, a switching device forsuccessively associating said sources of current with said main circuitand said relays with said thermionio relay, and a plurality of signalingdevices selectively operable under the control of said relays forindicating which of said branches is closed.

11. In a telephone system, a subscribers line, a plurality of normallyopen substation branches thereon, an electrical selective vdeviceassociated with eaoh of said branches, said several devices differingfrom each other in their selectivity, means at each substation foreiecting the closure of its branch, a pluralityof sources of current ofdifferent characteristics,means for associating said sources` insuccession with said subscribers line, and means responsive to the flowof'said electric currents through said selectivedevices for registeringwhich of said substation branches is closed.

12. InV a telephone system, a subscribers line, a plurality of normallyopensubstation branches thereon, a filter associated with each of saidbranches, said several filters being tuned respectively to be resonantto current of different frequencies, means at each substation foreffecting the closure of its branch, means for applying electriccurrents of different frequencies in succession to said subscribersline, and means responsive to the flow of said electric currents throughsaid filters for registering which of said substation branches isclosed.

13. In a telephone system, a subscribers line, a plurality of normallyopen substation branches thereon, a filter associated. with each of saidbranches, said several. filters being tuned respectively to be resonantto currents of different frequencies, means at each substation foreffecting the closure of its branch, means for applying electriccurrents of different frequencies in succession to said subscribersline, a thermionic relay adapted to be associated with said sub--scribers line responsive to the currents iiowing thereover through saidfilters, and a plurality of message registers individual respective-lyto said substation branches selectively controlled by said relay forregistering which of said branches is closed to initiate a call.

14. In a telephone system, a subscribers line, a plurality of normallyopen substation branches thereon, a filter associated with each of saidbranches, said several filters being tuned respectively to be resonantto currents of different frequencies, means at each substation foreffecting the closure of its branch, means for applying electric Lsaidthermionic` relay, means 'for associating vsaid relays successively withsaid thermionic relay, and a plurality of message registers individualrespectively to said substation branches and operable under control ofsaid relays for registering which of said branches isclosed to initiatea call.

- 15.111 a telephone system a subscribers line, la plurality of normallyopen substation branches thereon, a iilter associated With each of :saidbranches, said several fil- 'ters being tuned respectively to beresonant to current of different frequencies, means .at each substationfor effecting the `closure of its branch, sources of current of theJfrequencies to which said filters are resonant, ya therinionic relayassociated with vsaid ksubscribers line and operated'by current flowingthereover through any closed substation branch thereof from such of saidsources of current as are inthe resonance range of the filter of saidclosed branch, a plurality'of relays controlled by said `therlnionicrelay, a switching device for successively associating said sources ofcurrent with said line 4and said relays With said thermionic relay,

and a plurality of message registers individual respectively to saidsubstation branches selectively operable under the control of saidrelays for registering which of said branches is closed to initiate acall.

16. In a telephone system, a subscribers line, a plurality of normallyopen substation branches thereon, a filter associated with each of saidbranches, said several lilters being tuned respectively to be resonant-to currents of different frequencies, means at each substation foreffecting the closure of its branch, means for applying electriccurrents of different frequencies in succession to said subscribersline, a thermionic relay adapted to be associated with said line andoperated by current flowing thereover from any of said sources, aplurality of relays controlled by said therinionic relay, means forassociating said relays successively with said thermionic relay, aplurality of message registers individual respectively to saidsubstation branches and selec-

